What is it called when two singers sing together?

How do i attach images to my questions on

Which type of listening style would be most appropriate for the following scenario? you're going on vacation to visit your older brother. he is telling you which freeways and streets to take to get to his house. informational critical empathic

This is for my film class. if you would like to try writing your own play, having some experience in is a good idea. a. singing b. publishing c. theater d. editing